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5) During an auto power-up, the displays PROM sequencer is in a standby state. This standby mode of the display reduces power consumption approximately 15 percent. During the autopower on mode, the MCDPs switches are deactivated.
(3) Manual Power-Up and Self-Test (Fig. 5)
(a)
The manual power-up and self-test is initiated by pressing the ON/OFF light/switch. This sends a pulse signal to the power supply switching control and instructs the CPU to call up the power-up and latch routine.
(b)
The power-up and latch routine checks that the regulated 5 vdc power level has a minimum level of 4.75 vdc. If the level is within limits, the power-up and latch routine triggers a pulse circuit that sets the power regulators latching flip-flop, and provides a POWER LATCHED ON signal to the self-test manager module.
(c)
The POWER LATCHED ON signal to the CPU enables the self-test routines. The absence of an AUTO ON signal tells the CPU that a manual power-up has been done. Therefore, all of the following seven self-test functions are performed: 1) random access memory, 2) read only memory, 3) low-speed ARINC wrap-around, 4) high-speed ARINC wrap-around, 5) discrete wrap-around, 6) display, 7) lights. The self-test of the display and lights consists of turning on the annunciator lights and all segments of the 32 character display for approximately three seconds for operator verification. A successful self-test causes the CPU to enter FLIGHT FAULTS MODE. This is indicated by the FLT FAULTS annunciator lighting and a LAST FLT FAULTS ? message being displayed.
(d)
If a fault is found during the self-tests, the CPU generates an MCDP failure signal that holds the FAIL annunciator on. The FAIL annunciator stays lighted until a manual power-off is done. In addition to the FAIL annunciator staying lighted, the MCDP displays MCDP FAIL on the top line of the display. On the bottom line, a diagnostic message for shop use is displayed. The diagnostic messages are stored on volatile memory. The message must be manually recorded prior to removing the MCDP for repair. 1) The option pins are read by the CPU to determine the
airplane configuration, FMC, FCC, customer options, and parity. The option pin data is then stored for later use in the program routines.
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. INITIATE MANUAL POWER UP BY PRESSING ON/OFF BUTTON . A SELF-TEST IS CONDUCTED AND THE ABOVE TEST PATTERN SHOWN . AFTER 5 SECONDS, A SUCCESSFUL TEST IS INDICATED BY THE FAIL
AND GRD TEST LIGHTS EXTINGUISH . THE FLIGHT FAULTS MODE IS ENTERED
MCDP Manual Power Up and Self-Test
Figure 5
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(e) Manual Power-Down
1) A manual power-down signal is generated by pressing the ON/OFF lightswitch. This causes the CPU executive module to generate a TURN POWER OFF pulse. The pulse resets the power-on latch flip-flop to off. This enables the power-down routine which turns off the power supply switching control.
(4) Remote MCDP Operation (Fig. 6)
(a)
Remote MCDP operation uses a hand held MCDP remote control panel that is connected at the forward side of the P61 panel in the flight compartment. The remote panel switches are connected in parallel with the control switches on the MCDP.
(b)
The remote MCDP operation displays MCDP data on the EICAS display in the P-2 panel. The EICAS system accepts MCDP data when the CONFIG/MCDP switch is selected on the EICAS Maintenance Panel located on the P61 panel. The EICAS maintenance panel is disabled in flight through an air/ground relay.
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